class Person():

    def __init__(self, name, sex, age, id):
        self.__name = name
        self.__sex = sex
        self.__age = age
        self.__id = id

    def __del__(self):
        pass

    def eat(self):
        print("eating")

    def sleep(self):
        print("sleeping")

    def work(self):
        print("working")


class Student(Person):

    def __init__(self, school, sid):
        self.__school = school
        self.__sid = sid
        super(Student, self).__init__(name="", sex="", age="", id=0)

    def work(self):
        print("learning")


class Workers(Person):
    __count = 0

    def __init__(self, cname, technology, work_year):
        super(Workers, self).__init__(name="", sex="", age="", id=0)
        self.__cname = cname
        self.__technology = technology
        self.__work_year = work_year
        Workers.__count += 1

    def __del__(self):
        self.__count -= 1

    def work(self):
        print("worders work")

    def number(self):
        print(self.__count)


if __name__ == "__main__":
    w = Workers("123", "456", 10)